The invention relates to a display device comprising an electro-optical display medium between two supporting plates, a system of picture elements arranged in rows and columns, with each picture element being formed by picture electrodes arranged on the facing surfaces of the supporting plates, and a system of row and column electrodes for presenting selection and data signals by means of which a range of voltages dependent on the electro-optical display medium can be presented across the picture elements for the purpose of picture display.
A display device of this type is suitable for displaying alphanumerical information and video information by means of passive elector-optical display media such as liquid crystals, electrophoretic suspensions and electrochromic materials.
A display device ofthe type described in the opening paragraph is known from U.S. Pat. No. 4,811,006, issued March, 1989, in the name of the Applicant. In the device shown in this Application diodes are used as non-linear switching elements in an active matrix, namely two diodes per picture element. Two successive rows of picture elements each time have one row electrode in common. The drive mode is such that in television applications (for example, with a drive mode in accordance with the PAL or NTSC system) the information of two successive even and odd lines is presented across each picture element at an alternating polarity and at the field frequency. The information of a picture element is therefore determined by the average signal of two successive even and odd lines. Since each time two rows of picture electrodes are simultaneously written, because two successive rows each time have one row electrode in common, such a device provides little flexibility as regards the choice of colour filters to be used. In fact, this choice is limited to strip-shaped colour filters.
U.S. patent application Ser. No. 208,185, filed Jun. 16, 1988; in the name of the Applicant describes a picture display device of the type mentioned in the opening paragraph in which the row electrodes are not common and in which the rows of picture elements are separately driven without the omission of common row electrodes, leading to an increase of the number of connections.
This ensures a considerable freedom in the choice of the colour filters to be used.
This is possible by giving the picture elements a given adjustment per row by charging or discharging the capacitances associated with these picture elements after first having discharged or charged them too far (whether or not accurately).
To this end such a picture display device comprises means to apply, prior to selection, an auxiliary voltage across the picture elements beyond or on the limit of the voltage range to be used for picture display.
In the embodiment shown in the said Patent Application diodes are used as non-linear switching elements.